﻿/************************************************************************

   Extended Silverlight Toolkit

   Copyright (C) 2010-2012 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://extendedsilverlight.codeplex.com/license

   Please purchase a commercial version of this toolkit if you are using
   it in a commercial product. The commercial versions support the project,
   and also include more features for each control, priority support,
   source code, updates, removed watermark, and a proprietary license.

   Visit http://xceed.com and follow @datagrid on Twitter.

  **********************************************************************/

using System;

namespace Xceed.Silverlight.Data
{
  public sealed class PropertyChangedDescription
  {
    #region Static Fields

    public static readonly object UnsetValue = new NoValue();

    #endregion

    #region Constructors

    public PropertyChangedDescription( string propertyName )
      : this( propertyName, PropertyChangedDescription.UnsetValue )
    {
    }

    public PropertyChangedDescription( string propertyName, object oldValue )
    {
      if( propertyName == null )
        throw new ArgumentNullException( "propertyName" );

      this.PropertyName = propertyName;
      this.OldValue = oldValue;
    }

    #endregion

    #region PropertyName Property

    public string PropertyName
    {
      get;
      private set;
    }

    #endregion

    #region OldValue Property

    public object OldValue
    {
      get;
      private set;
    }

    #endregion

    #region Private NoValue Nested Type

    private class NoValue
    {
    }

    #endregion
  }
}
